6alpha-methylpregnane derivatives and process for preparing same



3,028,380 Ga-METHYLPREGNANE DERIVATIVES AND PROCESS FOR PREPARING SAME Vladimir Petrow and David Morton Williamson, London, England, assignors to The British Drug Houses Limited,

London, England, a British company a No Drawing. Filed June 30, 1959, Ser. No. 823,820

Claims priority, application Great Britain July. 9, 1958 g 6 Claims. (Cl. 260-4395) This invention is for improvements in or relating to organic compounds and has particular reference to the preparation of new 6:16-dimethylpregnane derivatives which are of value as intermediates in the preparation of l7a-hydroxyand 17a-acyloxy-6:16-dimethyl derivatives of pregnane which are valuable as progestational agents.

In particular 17u-acetoxy-6a,16-dimethylprogesterone is found to be 100 times more potent than dimethisterone (60:,21 dimethylethisterone; 60:,21 dimethylanhydrohydroxy-progesterone) in the Clau'berg assay. As dimethisterone (6a,2l-dimethylethisterone) is known to be slightly more than times as active as anhydrohydroxyprogesterone (ethisterone) in the Clauberg assay (David, Hartley, Millson and Petrow, J. Pharm. Pharmacol., 1957, 9, 929), it will be apparent to those skilled in the art that 17a-acetoxy-6a,l6-dimethylprogesterone is a progestational agent of quite unexpected and remarkable potency, and its preparation a matter of importance.

It is an object of the present invention to provide the new compound 6oz:16-dimethylpregna-4:l6-dien-3z20- dione (1) O OMe I In in (I) The above compound is a valuable and convenient starting material for the preparation of the potent progestational agent 17a-acetoxy-6u,16-dimethylprogesterone. The conversion into this progestational agent may be accomplished by converting the 3-oxo-derivative, 6a:16-dimethylpregna-4zl6-dien-3:ZO-di-one (I) into the 16oc,17aepoxide, converting this l6a,17a-epoxide into a l7u-hydroxy-l6B-hal0-16wmethyl intermediate by reaction with a halohydrin, reductively removing the halogen atom and acetylating the tert.-h'ydroxyl group at C The present invention also provides the intermediate pyrazoline 6a-methyl-16: 17- (2' 3 '-diazacyclopent-2'-eno) pregn-4-ene-3z20-dione (II) Me (II) According to the present invention there is provided a process for the preparation of 6azl-dimethylpregnanited States Patent Patented Apr. 3, 1962 "ice O OMe Me (III) with diazomethane to yield the corresponding :,17amethylene diazo derivative (II) or pyrazoline and themally decomposing the pyrazoline.

Addition of diazomethane to the starting material (III) is preferably performed in an unreactive organic solvent such as diethyl ether and the reaction mixture allowed to stand at room temperature for periods of 16 to 40 hours, and the pyrazoline subsequently isolated by removal of the solvent by evaporation and crystallisation of the residue.

Decomposition of the pyrazoline (II) to yield the 6: 16- dimethylpregn-ane derivative (I) may readily be performed by heating the pyrazoline under reflux in an inert organic solvent of B.P. approximately the same as the M.P. of the pyrazoline, such as dibutyl ether, for 3 to 5 hours. p-Cymene and ethylene glycol are other solvents suitable for effecting this thermal decomposition.

Following is a description by way of example of a method of carrying the invention into effect.

EXAMPLE 1 6a-Methyl-16:17-(2':3'-Diazacyclopent-2eno)pregn- 4-ene3:20-Di0ne (II) 6umethylpregna-4zl6-diene-3:ZO-dione (III) (1 g.) dissolved in methanol (10 ml.) was treated with diazomethane (1 g.) in ether (30 ml.) overnight at room temperature. Excess diazomethane was destroyed by addition of dilute acetic acid and the ether extracts were washed with water, sodium bicarbonate solution, water and dried. After removal of the ether the residue was crystallised from methanol yielding 6u-methyl-16:17- (2 3-diazacyclopent-2-eno) pregn-4-ene-3 :20-dione (H) prisms, M.P. 153 to 154 C., M1 +1l2 (c., 0.364 in chloroform),

7&2? 238 to 239 mu, 6 16,707 I 6 02:1 6 -Dimethylpregna-4:1 6-Diene-3 :ZO-Dione (I) The foregoing pyrazoline (II) (500 mg.) was heated under reflux in dibutyl ether (20 ml.) for 2 hours. The dibutyl ether was removed under reduced pressure and the residue was crystallised from methanol to give 6x216- dimethylpregna-4:16-diene-3z20-dione (I), M.P. 188 to 190 C., [121 +65 (c., 0.338 in CHClg),

r512? 242 to 244, e=23,322

We claim:

1. A process for the preparation of 6a:16-dimethylpregna-4:l6-dien-3z20-dione which process comprises reacting 6a-methylpregna-4:16-diene-3:20-dione with diazomethane to yield the corresponding 160:,1700-4'1'181113'16116 diazo derivative and heating to thermally decompose the said 16a,17 x-methylene diazo derivative.

2. A process as claimed in claim 1 wherein the diazomethane in diethyl ether is added to the steroid starting material and the reaction mixture allowed to stand at room temperature for periods of 16 to 40 hours.

3. A process as claimed in claim 1 wherein the l6u,17- methylene diazo derivative is decomposed by heating un- 3 4 der reflux in an inert organic solvent of B.P. approidmate- 6. 6u-methyl-16:17-(2':3'-diazacyclopent-2'-eno-preg11- ly the same as the MP. of the IMAM-methylene diazo 4-ene-3z20-dione. derivative.

4. A process as claimed in claim 3 wherein the inert References Cted the file of thls Patent organic solvent is dibutyl ether and the heating under re- 5 UNITED STATES PATENTS flux is out for 3 To 5 hours- 2,880,213 Loken et a1 Mar. 31, 1959 5. 6uzl6-dimethylpregria-4z16dien-3:20-dione. 2,888,457 Beyler et a1 May 26, 1959 

1. A PROCESS FOR THE PREPARATION OF 6A: 16-DIMETHLPREGNA-4:16-DIEN-3:20-DIONE WHICH PROCESS COMPRISES REACTING 6A-MEHTYLPREGNA-4:16-DIENE-3:20-DIONE WITH DEAZOMEHTANE TO YIELD THE CORRESPONDING 16A,17A-METHYLENE DIAZO DERIVATIVE AND HEATING TO THERMALLY DECOMPOSE THE SAID 16Q,17A-METHYLENE DIAZO DERIVATIVE.
 6. 6A-METHYL-16:17(2'':3''-DIAZACYCLOPENT-2''-ENO-PREGN4-ENE-3:20-DIONE. 